function zTable(){
return "Use the Reduced Pressure (Pr), Reduced Temperature (Tr) and this graph to estimate the Compressibility Factor Z, and enter it into the 'Calculator.'";
}
function calculateConstants() {
var Tc = document.ccform.Tc.value * 1 + 460;
var Pc = document.ccform.Pc.value;
var T = document.ccform.T.value * 1 + 460;
var P = document.ccform.P.value;
var Tr = T / Tc;
var Pr = P / Pc;
if (!isNaN(Pr) && (Pr != Number.POSITIVE_INFINITY) && (Pr != Number.NEGATIVE_INFINITY) &&
!isNaN(Tr) && (Tr != Number.POSITIVE_INFINITY) && (Tr != Number.NEGATIVE_INFINITY)) {
document.ccform.Pr.value = round(Pr);
document.ccform.Tr.value = round(Tr);
}
else {
document.ccform.Pr.value = "error";
document.ccform.Tr.value = "error";
}
}
function round(x){
return Math.round(x*100)/100;
}
function showGraph() {
var Pr = document.ccform.Pr.value;
var Tr = document.ccform.Tr.value;
var graph1, graph2, graph3, graph4;
if (screen.width < 950){
graphWin= open("", "displayWindow",
"width=700,height=530,status=no,toolbar=no,menubar=no");
graph1=" ";
graph2=" ";
graph3=" ";
graph4=" ";
}
else{
graphWin= open("", "displayWindow",
"width=845,height=680,status=no,toolbar=no,menubar=no");
graph1=" ";
graph2=" ";
graph3=" ";
graph4=" ";
}
graphWin.document.open();
graphWin.document.write("Compresability Factor Chart");
graphWin.document.write("");
if ((Pr <= 0.10) && (Tr <= 2.0)){
graphWin.document.write(graph1);
}
else if ((Pr <= 1.0) && (Tr <= 5.0)){
graphWin.document.write(graph2);
}
else if ((Pr <= 10.0) && (Tr <= 3.5)){
graphWin.document.write(graph3);
}
else {
graphWin.document.write(graph4);
}
graphWin.document.write("The Reduced Temperature (Tr) is represented by a trace on the graph. The Reduced Pressure (Pr) is represented by a vertical line. Locate the spot on the graph where the Tr Trace and the Pr line intersect, and then follow the corresponding horizontal line to the left to obtain the Compressibility Factor Z.");
graphWin.document.write("");
graphWin.document.close();
}
